There are several positions in the job market that require drug testing. For instance, if you are a driver of a semi-truck or bus driver, you must take a drug tests as well as submit to random drug testing during, prior to, and during your employment.

It is estimated by the U.S. Department of Labor that drug use in the workplace is a major expense to businesses due to loss time, accidents, worker's compensation cases and health care. This major expense totals up to approximately $75 billion to $100 billion each year.
Interestingly, the number of drug users appears to have fallen, although it could also mean that individuals have just gotten smarter about cheating on drug tests. In 1987, a national testing laboratory found that 18.1% of all workers tested positive for drugs. However, 10 years later in 1997, that number went down to 5.4%.

The majority of drug testing is done off the business site at a collection site that performs the test and either offers laboratory services or sends the samples to a laboratory for analysis. Negative results typically come back within 24 hours. However, businesses do have access to instant drug testing kits. These operate similar to that of your typical home pregnancy test. There are also other testing methods available to employers including Saliva Drug Tests and Hair Follicle Drug Testing.

Businesses should know that one of the most common explanations for people who fail a drug test for marijuana is that they were exposed to "second hand" marijuana smoke. To avoid this, most labs will set a higher threshold for THC, the metabolite of marijuana that is stored in the body's fat.
To try and reduce cheating on a pre-employment drug test is to specify that the person take their drug test at a specific time and date. This is to reduce the ability of the person to wait until the drugs are out of their system.

Each drug and each person is different, but most drugs will stay in a person's system about two to four days. Chronic users of drugs can be detected for up to 14 days or often much longer. Sedatives can be in the person's system for up to 30 days.

Most employers will utilize a drug test referred to as a "five panel test." This tests for marijuana (THC), cocaine, opiates (morphine and codeine), PCP and amphetamines, including methamphetamines. Some employers may utilize the even more stringent test including a 10-panel test that also tests for prescription drugs, both legal and illegal.